Funmum UK has plus size maternity styles for
all occasions. Collections range from daywear to evening wear and
offer to size 20. They have Combats, Distressed Jeans & Black
Bengalins to size 22 in petite and long lengths. Good choice in
the plus size 16-20 bracket

Tiffany
Rose MaternityLovely
maternity clothing up to plus size 18-20. They have been featured
in "Pregnancy" magazine, and Sky TV's Style Academy. They
have plus size maternity tops, bottoms, swimwear, dresses, evening
wear and even plus size maternity wedding dresses and bridesmaids
dresses. Use your pre-pregnancy size as a guide to fit.
Their stunningly attractive fashion makes pregnancy look even more
beautiful.

Bumps Maternity, based in
Sunderland, have a plus size section which has plus
size tops and bottoms to size 26, and Bravado Supreme maternity
bras to size 46H, as well as a comprehensive range of accessories
like support belts.